/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.filters;

import org.apache.juli.logging.Log;
import org.apache.tomcat.util.IntrospectionUtils;
import org.apache.tomcat.util.res.StringManager;

import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import java.util.Enumeration;

/**
 * Base class for filters that provides generic initialisation and a simple
 * no-op destruction.
 *
 * @author xxd
 */
public abstract class FilterBase implements Filter {

	protected static final StringManager sm = StringManager.getManager(Constants.Package);

	protected abstract Log getLogger();

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		Enumeration<String> paramNames = filterConfig.getInitParameterNames();
		while (paramNames.hasMoreElements()) {
			String paramName = paramNames.nextElement();
			if (!IntrospectionUtils.setProperty(this, paramName,
					filterConfig.getInitParameter(paramName))) {
				String msg = sm.getString("filterbase.noSuchProperty",
						paramName, this.getClass().getName());
				if (isConfigProblemFatal()) {
					throw new ServletException(msg);
				} else {
					getLogger().warn(msg);
				}
			}
		}
	}

	@Override
	public void destroy() {
		// NOOP
	}

	/**
	 * Determines if an exception when calling a setter or an unknown
	 * configuration attribute triggers the failure of the this filter which in
	 * turn will prevent the web application from starting.
	 *
	 * @return <code>true</code> if a problem should trigger the failure of this
	 * filter, else <code>false</code>
	 */
	protected boolean isConfigProblemFatal() {
		return false;
	}
}
